Can I edit tenants on a tenancy record?

There is an edit button next to tenants where they are listed on the 'Tenants' tab of a tenancy record. This allows you to edit the payment reference, rent and deposit amounts, next rent due date and rent period only. If the reason you want to edit a tenant is because they are leaving a shared tenancy mid-term, then this isn't possible - see the What do I do if a tenant in a shared tenancy gives notice and moves out? FAQ for information on this.